Abstract: A high-efficiency portable spa is provided for therapeutic and recreational use which includes a tub, a flow generator for circulating water in the tub, and a two-section insulating cover. A heat generator is located adjacent an outlet of the flow generator uses a constriction member in a fluid passageway to frictionally generate heat from the passage of fluid therein and also to reintroduce water circulating through a heat scavenging coil surrounding the flow generator. The tube is advantageously provided with a shell, a frame for supporting the shell, a flexible web barrier surrounding the frame, a skirt surrounding the web, and insulating foam which adheres to the web barrier so that, during curing, the skirt is isolated from shrinkage, crinkling or warping. The cover is provided in two sections and hinged therebetween. The edge of the cover rests on the shell of the tub, and one of the sections may be folded out of the way to provide access to the tub while substantially insulating the remainder.

Abstract: A projectile is propelled from the gun when a valve that controls the gas storage chamber of the gun is momentarily unseated, thereby admitting a short burst or charge of gas into the space immediately behind the projectile. The barrel that confines and controls the projectile during its movement out of the gun is itself driven rearwardly by spring action to accomplish unseating of the valve through an actuating stem at the rear of the barrel, and during such rearward movement of the barrel, the projectile is carried therewith so as to reduce the volume of the space behind the projectile in which the gas may expand before acting upon the projectile.

Abstract: There is herein disclosed an air gun having a breech block assembly, including a plurality of mating molded plastic members defining a guideway for a pivotally mounted projectile transfer member, movable during cocking of the gun from a firing position holding a projectile in alignment with the gun barrel to a loading position to receive another projectile and back to the firing position, with sealing means being provided to effect sealing engagement between the projectile transfer member and the molded plastic members of the breech block assembly in the firing position whereat the projectile is transferred from the projectile transfer member to a firing chamber provided in one of the molded plastic members by air pressure at the beginning of a firing cycle and held in the firing chamber in sealing engagement therewithin during an intermediate portion of the firing cycle and then discharged from the firing chamber through the gun barrel upon application of predetermined high pressure air toward the end of the